Among concerns for generally immobile persons are medical conditions that form blood clots, such as deep vein thrombosis (DVT) and peripheral edema. Such persons include those undergoing surgery, anesthesia, and extended periods of bed rest. These blood clotting conditions generally occur in the deep veins of the lower extremities and/or pelvis. Veins such as the iliac, femoral, popliteal, and tibial veins return deoxygenated blood to the heart. When blood circulation in these veins is retarded due to illness, injury, or inactivity, there is a tendency for blood to accumulate or pool. A static pool of blood may lead to a blood clot, which can interfere with cardiovascular circulation. More seriously, the blood clot can break loose and migrate. A pulmonary embolus, which may be life threatening, can form if the blood clot blocks a pulmonary artery.
Vascular compression systems are used to promote flow of bodily fluid. For example, conventional vascular compression systems include a compression garment fluidly connected to a controller that cyclically inflates the compression garment. The cyclical inflation of the compression garment enhances blood circulation and decreases the likelihood of DVT. Some compression garments are adapted for application to a foot of a person for compressing the foot. Other compression garments are adapted for application to a leg of a person for compressing the leg. In some instances, compression garments include a foot portion and a leg portion. In general, conduits are provided for fluidly connecting the compression garment to the controller. Some vascular compression systems include portable controllers that are much smaller and mountable on the compression garment, so the patient is not tethered to a device by tubing that restricts motion and may become tangled. Portable compression systems are believed to enhance patient compliance due to convenience of use.
Conventional controllers tend to create a fair amount of noise when inflating the compression garment. In general, efficacious compression therapy requires inflation of the compression garment at rapid flow rates. Conventional controllers generally include pressurizers (e.g., pumps) for generating pressurized air for inflating compression garments, and such pressurizers tend to create noise when generating the pressurized air. Moreover, the pressurized air tends to create noise as it enters inflatable chambers on the compression garment.